Schizophrenia is usually classified based on clinical presentation. However, the conventional paranoid–disorganised–residual distinctions have had limited clinical utility. Here we draw on the evidence for differences in pathophysiology underlying treatment response to propose a subclassification based on neurobiology to guide diagnostic testing and treatment.

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A neurobiological hypothesis for the classification of schizophrenia: type a (hyperdopaminergic) and type B (normodopaminergic)

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A neurobiological hypothesis for the classification of schizophrenia: type a (hyperdopaminergic) and type B (normodopaminergic)

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In the past 3 years O.H. has received investigator-led grants and/or served as a speaker/consultant for Eli Lilly, Roche, Leyden-Delta, Lundbeck, Servier and Janssen-Cilag (J&J). S.K. has received grant support from GlaxoSmithKline, GW and Roche and has served as a one-off consultant and/or speaker for AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Envivo, Janssen (J&J), Otsuka, Pfizer and Takeda, and serves on scientific advisory boards for Lundbeck and Roche.

Footnotes

Declaration of interest

In the past 3 years O.H. has received investigator-led grants and/or served as a speaker/consultant for Eli Lilly, Roche, Leyden-Delta, Lundbeck, Servier and Janssen-Cilag (J&J). S.K. has received grant support from GlaxoSmithKline, GW and Roche and has served as a one-off consultant and/or speaker for AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Envivo, Janssen (J&J), Otsuka, Pfizer and Takeda, and serves on scientific advisory boards for Lundbeck and Roche.

eLetters

More questions

Prasanna N. de Silva, Consultant Old Age Psychiatrist
09 September 2014

Could the authors address the following questions?

1. How does this hypothesis differ from Crow's Type 1 and 2 division?As you know, there was correlation between imaging and clinical findings for this separation.2. How does your hypothesis fit with presence or otherwise of hypofrontality?3. What are the clinical implications of your hypothesis as to which patients with schizophreniform episodes merit long term continuation of antipsychotics and which might benefit from discontinuation at 6 months?Thank you

Patients with type B (normodopaminergic) schizophrenia are more likely to be treatment resistant and subsequently have a poorer outcome1. It would be interesting to consider whether there are any phenomenologicaldifferences in the psychotic or cognitive symptoms experienced by patientswith type A or B schizophrenia. Nevertheless, the identification of a potential PET imaging biomarker to assess potential treatment resistance in schizophrenia is certainly good news2. However, it is important to consider how these findings can be translated into clinical practice. There has been a vast amount of neuroimaging research which has significantly increased our understanding of the structural and functionalcorrelates of psychiatric disorders, however this wealth of knowledge has had little impact clinically3. This has been partly related to access, butalso because psychiatric disorders are syndromes that represent the expression of multiple genetic and biological pathways. However with the type A/B distinction there is potential utility of pattern recognition tools in separating patients based on a single molecular target. More research is therefore needed to assess the correlation between striatal dopamine function and treatment response. As the evidence for imaging and other biomarkers becomes stronger they will play a bigger role in aiding diagnosis and assessing outcome. It is therefore important that the links between neuroscience and psychiatry are explicit in training4 and the scientific underpinnings of the specialty are explicit within mental health services and in our interactions with patients and the public in general.

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